Source apportionment to PM10 in different air quality conditions for Taichung urban and coastal areas, Taiwan

PM2.5 and PM2.5-10 samples were collected between August 1998 and March 1999 at Taichung urban and coastal sites. The major objective in this study was to identify the source contributions to PM10 in different air quality conditions. Principal component analysis with varimax rotation and a chemical mass balance model were used to qualify and quantify, respectively, the source contributions to PM10. Vehicle emissions was the most important source of PM10 at the urban site, followed by crustal materials, secondary aerosols, biomass burning, industrial emissions and marine spray. There was a similar pattern of sources at the coastal site, except that marine spray was found more significantly than the urban site. Although biomass burning and secondary aerosols were not main sources during clean air quality periods, they were the influential sources causing the increase of PM10 to "episodic" levels at both sites. (C) 2004 Elsevier Ltd. All rights reserved

Empirical Models to Predict Parsimoniously the Mass and Number Concentrations of Ultrafine Particulate in Ambient Atmosphere

The main objective of this study was to develop parsimonious empirical models for predicting the mass and number concentrations of ultrafine particulate (UFP, aerodynamic diameter < 0.1 or 0.18 mu m) in the atmospheric environment. We found strong correlations existed between the mass/number concentration of UFP and the mass concentration of PM(2.5) (aerodynamic diameter < 2.5 mu m) by fitting the experimental data. Therefore, we were easily able to obtain UFP mass and number concentrations by using the presented empirical models. The empirical equations should be used with care since limitations existed

Carbonaceous Aerosol Measurements at Coastal, Urban, and Inland Sites in Central Taiwan

The concentrations of elemental carbon (EC) and organic carbon (OC) of particulate matter (PM)2.5 were investigated at coastal, urban, and inland sites in central Taiwan during October 1999 and March 2000, and the carbon contents were analyzed using a total organic carbon analyzer (TOC). The results showed that the average EC concentrations at the various sites were from 2.7-4.4 g/m3, while the mean OC concentrations were from 6.9-12.3 g/m3. Both higher EC and OC levels were found in inland areas. Good correlations of OC and EC were found in coastal and urban areas, indicating that OC was mainly from the primary combustion emissions, whereas OC was weakly correlated with EC at the inland sites, suggesting that the contributions of OC were unrelated combustion sources (i.e., secondary organic carbon). The optimal Deming regression was used to estimate the ratio of OC/EC, leading to calculate the amount of secondary organic aerosols in this study. On average, secondary organic carbon constituted 13%-48% of the total organic carbon for PM2.5 with high levels observed in inland areas. Moreover, higher secondary OC concentration was observed at low wind speed, high relative humidity and high oxidants sum (O3 + NO2) levels atmosphere

Characteristics of aerosols collected in central Taiwan during an Asian dust event in spring 2000

Aerosol samples for PM2.5 and PM2.5-10 were collected at four locations in central Taiwan from 26 to 31 March 2000, a period that experienced exceedingly high PM levels from 29 to 30 March due to the passage of an Asian dust storm. The samples were analyzed for mass, metallic elements, ions, and carbon. The purpose of this paper is to investigate the influence of the dust storm on the characteristics of local ambient particulate matter. The results indicate that the concentrations of the crustal elements Ca, Mg, Al, Fe and the sea salt species Na+ and Cl- in PM2.5-10 during the dust episode exceed the mean concentrations in the non-dust period by factors of 3.1, 2.9, 2.6, 2.2, 2.3 and 2.1 respectively. Enrichment factors of Ca, Fe, and Mg in PM2.5-10 during the dust event are close to unity, indicating that these elements are from soil. Reconstruction of aerosol compositions revealed that soil of coarse particulates elevated approximately 50% in the dust event. It is noted that during the dust event, the ratio of Mg/Al in PM2.5-10 ranged from 0.21 to 0.25 while that of Ca/Al ranged from 0.6 to 0.9, levels more constant than those obtained in non-dust period. (c) 2005 Elsevier Ltd. All rights reserved

Quantification on the source/receptor relationship of primary pollutants and secondary aerosols by a Gaussian plume trajectory model: Part II. Case study

This study applies a newly developed model, the Gaussian trajectory transfer-coefficient model (GTx) (Part I, Atmos. Environ., this issue), to Taichung City. Two fossil-fueled power plants are situated in the vicinity of Taichung City. The model was calibrated in the winter of 1997 and verified throughout the entire following year of 1998. The results indicate that the correlation coefficients (r(2)) for the daily concentrations of various pollutants were in the range of 0.49-0.83 during the calibrated period and in the range of 0.37-0.71 during the verification period. The advantage of GTx is that the source/receptor relationship of sources can be determined in a single model run. It shows that line sources contributed to 62% of CO, 65% of NOx and 21% of nitrate aerosol; point sources contributed to 46% of SO2, 57% of sulfate aerosol and 27% of PM2.5; and area sources contributed to 18% of PM2.5 and 60% of PM2.5-10 during the PM10 episodes in 1998. During the episodes TC power plant contributed to more fractions of pollutants than during non-episode days since the sea breeze blew its plume to the city. According to our analysis, if a fossil-fueled power plant is built at 1-3 days upwind of a city with NOx emitted from an effective stack height within 100-800m, it has a higher potential to deteriorate the air quality of the city by increasing the concentration level of nitrate aerosols under unfavorable meteorological conditions. (C) 2003 Elsevier Ltd. All rights reserved

Compositions and source apportionments of atmospheric aerosol during Asian dust storm and local pollution in central Taiwan

A study has been carried out on water soluble ions, trace elements, as well as PM(2.5) and PM(2.5-10) elemental and organic carbon samples collected daily from Central Taiwan over a one year period in 2005. A source apportionment study was performed, employing a Gaussian trajectory transfer coefficient model (GTx) to the results from 141 sets of PM(2.5) and PM(2.5-10) samples. Two different types of PM(10) episodes, local pollution (LOP) and Asian dust storm (ADS) were observed in this study. The results revealed that relative high concentrations of secondary aerosols (NO (3) (-) , SO (4) (2-) and NH (4) (+) ) and the elements Cu, Zn, Cd, Pb and As were observed in PM(2.5) during LOP periods. However, sea salt species (Na(+) and Cl(-)) and crustal elements (e.g., Al, Fe, Mg, K, Ca and Ti) of PM(2.5-10) showed a sharp increase during ADS periods. Anthropogenic source metals, Cu, Zn, Cd, Pb and As, as well as coarse nitrate also increased with ADS episodes. Moreover, reconstruction of aerosol compositions revealed that soil of PM(2.5-10) elevated approximately 12-14% in ADS periods than LOP and Clear periods. A significantly high ratio of non-sea salt sulfate to elemental carbon (NSS-SO (4) (2-) /EC) of PM(2.5-10) during ADS periods was associated with higher concentrations of non-sea-salt sulfates from the industrial regions of China. Source apportionment analysis showed that 39% of PM(10), 25% of PM(2.5), 50% of PM(2.5-10), 42% of sulfate and 30% of nitrate were attributable to the long range transport during ADS periods, respectively